MY2008 Saab 9-3 – Powertrain

Unique ‘Tri-fuel’ Engine Line-up

• Choice of 6 gasoline, 3 diesel and 2 Saab Biopower (E85) options
• Range-topping all-aluminum 280 hp/206 kW 2.8V6 Turbo with Saab XWD
• New 180 hp/132 kW two-stage turbo diesel: class-leading performance/economy
• Aluminum 2.0 turbos offering 150 hp/110 kW, 175 hp/129 kW or 210 hp/155 kW

All aluminum 2.8-liter V6 Turbo
This sophisticated engine has a 60º vee-angle between its cylinder banks for perfect balance and combines excellent multi-valve refinement with outstanding performance. Exclusive to Aero variants, it develops 280 hp/206 kW and exceptional torque of 400 Nm, when offered with Saab XWD, and 255 hp/188 kW and 350 Nm in front-wheel drive applications. The all aluminum construction provides a light and compact architecture, well suited to its transverse installation.

The cylinder heads, each with double chain-driven overhead camshafts operating four valves per cylinder, are of high specification aluminum. The design ensures enhanced heat resistance under 85 bar cylinder pressures, as well as minimum maintenance costs. The pistons have hard anodized ring grooves for durability and under-skirt oil jet cooling. The steel con-rods are strengthened by sinter-forging, a process that involves molding metal in a powered form. The exhaust valves are filled with sodium to further enhance cooling. The cylinders have cast iron liners and a bore/stoke of 89.00 / 74.8 mm.

For improved engine breathing, variable cam phasing on the inlet side is electronically controlled and hydraulically actuated, allowing continuously variable adjustment through 50º of crankshaft rotation. On the road, this translates to a more flexible power delivery and better fuel economy under different engine loads.

A die-cast aluminum oil sump is designed to increase structural stiffness and the strong, four-bearing crankshaft is made from micro-alloy forged steel, a specification more commonly seen in competition performance or diesel engines. Together with a dual-mass flywheel, these elements further reduce unwanted noise and vibration, ensuring smooth and refined performance.

The twin-scroll, water-cooled Mitsubishi TDO4-15TK turbocharger, operates at 0.6 bar maximum boost with intercooling and an integral by-pass valve. It is mounted centrally above the transmission and fed by both banks of cylinders. The use of two separate inlet tracts, one for each cylinder bank, separates the exhaust gas pulses, improving gas flow, reducing energy losses and raising turbocharger efficiency. The turbine wheel is made from a special high-grade steel alloy, commonly used in the turbocharged engines of world championship rally cars, which is resistant to erosion, cracking and creeping under high temperatures and centrifugal forces.

Also unique are double-skin exhaust manifolds, which are hydroformed with stainless steel liners to improve cold start emissions by minimizing heat absorption to the manifold. Air injection into each manifold for up to 30 seconds after a cold start also helps the central pre-catalyst, positioned upstream of the main catalytic converter, achieve ‘light off’, its effective working temperature, as early as possible.

The 32-bit engine management system, with software calibrated specifically for the Saab 9-3 application, utilizes a torque-based engine control strategy and direct coil-over-plug ignition with a robust engine-mounted control unit. Ignition timing, fuel injection, turbo boost pressure, air mass measurement and the throttle setting are all key engine functions controlled by the software.

The sophisticated control strategy is designed to deliver smooth performance in all driving conditions. For two-wheel drive, it can modulate engine torque in low-traction conditions, helping provide confident, sure-footed driving. Variable fuel pressure further contributes to smooth idle and driving characteristics.

For driving comfort, control of the electronic throttle through the movement of the accelerator pedal is programmed to be sensitive to different driving conditions, with greater pedal movement introduced at lower vehicle speeds, such as when maneuvering or parking. At low engine speeds, the engine control system also brings the turbo in quickly by momentarily opening the throttle slightly more than requested by the driver.

In 280 hp/ 206 kW or 255 hp/ 188 kW specification, maximum torque is generated from just 1,800 rpm all the way to 5,000 rpm, with 90 per cent of this value available from an exceptionally low 1,500 rpm. Under a full throttle load at take-off or low engine speeds, 90 per cent of maximum acceleration is delivered within one second.

The fast, but controlled, torque build-up immediately above the 720 rpm idle speed is delivered with a turbine-like smoothness, giving impressive on the road performance. The 9-3 Aero Sport Sedan can accomplish the zero to 100 kph dash in a rapid 6.7 seconds (FWD) or 6.3 seconds (projected) with Saab XWD, new performance ben

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